In recent years, many of display devices of various electronic devices, for example, display of mobile phone, include a liquid crystal display and a transparent electrostatic capacitance touch panel laminated over the surface of the liquid crystal display, and in such display devices, an instruction image displayed on the liquid crystal display is referred to, a location where the instruction image is displayed is touched by a finger or the like, and information corresponding to the instruction image can be input.
In an electrostatic capacitance touch panel in which transparent electrodes are formed over a transparent insulating substrate (for example, glass substrate), the outline of the electrodes is not prominent even if there is a difference of optical refractive index or reflection rate between the electrode and the insulated area if the width of the insulated area between the electrodes is 30 μm or less for example, according to the limit value of recognition of the shape by naked eyes.
However, in the manufacture of an electrostatic capacitance touch panel, after a transparent conductive film (for example, ITO film) is formed over one surface of an insulating substrate, an insulated area is formed by etching the transparent conductive film by a laser etching method or photolithography, and a first electrode to which a signal for detecting position is applied and a second electrode for outputting electrostatic capacity generated between the first electrode and the position to which a finger or the like approaches are formed. Note that, an optical layer for lowering the difference of the refractive index may be provided between the insulating substrate and the transparent conductive film.
At this time, if the transparent conductive film is etched so that the width between the electrodes is 30 μm or less over the whole length of the insulated area, it becomes highly possible that adjacent electrodes are short-circuited as an error of manufacture, and the ones with electrode short circuit are disposed as defective products. In addition, if the transparent conductive film is etched so that the width of the electrodes is 30 μm or less over the whole length of the insulated area, because the distance between the adjacent first electrode and second electrode becomes short, the line of electric force from the first electrode toward the second electrode via a space over the operation surface of the electrostatic capacitance touch panel is decreased. As a result, because the change of the line of electric force when a finger or the like touches or approaches becomes less, there will be a problem of decreased detection sensitivity.
Therefore, a technique is disclosed in which the width of the insulated area between the electrodes is made to be wider than 30 μm except the intersection of the electrodes, and a dummy electrode is provided to the portion with wide width of the insulated area between the electrodes in a floating state without short circuit to keep the detection sensitivity high and conceal the outline of the electrodes (Japanese Patent No. 4720857).